Improvement in dies for making watch-case caps and backs



s. c. LEWIS. Dies for Making Watch-Basefiaps and Backs.

N0. 140,424, PatentedJuIyhIBZS.

AM. PHoro-umosmPH/c c0. NX(0sanRNE3' mums) UNITED STATES PATENT OFFICE.

SILAS O. LEWIS, OF BROOKLYN, NEW YORK.

IMPROVEMENT IN DIES FOR MAKING WATCH-CASE CAPS AND BACKS.

Specification forming part of Letters Patent No. 140,424, dated July 1, 1873; application filed March 29, 1873.

To all whom it may concern:

Be it known that I, SILAS O. Lnwrs, of Brooklyn, in the county of Kings and State of New York, have invented a new and Improved Die for Striking out Gold Watch Case Gaps and Backs, of which the following is a specification:

In the accompanying drawing, Figure 1 represents a vertical section of my improved die on the line 0 0, Fig.2; and Fig. 2 is a top view of the same.

Similar letters of reference indicate corresponding parts.

The object of my invention is to construct a die for the purpose of striking out the backs and caps of gold-watch cases without spinning the same. i

It is well known that the covers of silver and other metals may be stamped out by means of suitable dies, but that gold covers could not be struck directly, as, on account of the elasticity of the metal, the flat surface was not obtained. The covers assumed a curved oval shape, and required a special spinning pro-.

form and material, but having, instead of a flat surface, an elevation, which gradually increases from the circumlerence toward the center, adjusted to the elasticity of the gold and the thickness of the covers, resulting in the striking of perfectly-flat covers.

In the drawing, A represents the body of the die, of suitable shape and material; B, the recess therein for the gold covers to be stamped.

The curved circumference a, instead of being connected by a plane, as has been the case, is slightly elevated toward the center of the recess 13, forming an indented surface, I).

The gold covers stamped by dies having such elevations will, if the same are adjusted exactly With the corresponding degree of elasticity of the metal, produce a perfectly-even plane more accurately than if they had been spun out. The manufacture of gold caps and backs will, therefore, be greatly simplified by the use of such dies.

Having thus described my invention, I claim as new and desire to secure by Letters Patent-- The die A B, having circular concavity a and central convexity b, as and for the purpose described.

Witnesses: SILAS O. LEWIS.

PAUL GonPEL, '1. B. MosHER. 

